Latest upset shows Serena can no longer dominate as part-timer

But it's those "ifs" and "whens" and "whats" that are becoming more and more problematic. Serena is 30 now, the magic age when the skills of even the best players supposedly start their irretrievable decline. Serena is often injured; and when she does play, she comes wrapped in tape like a knight swaddled in armor. Her focus is, as ever, erratic. There was a time when Serena's aura was worth a few games each set. She'd pound aces and hammer forehands and play "big points" as though they were "small points" and ... presto, the wins would materialize.

That aura isn't what it once was. There's a new cohort of players that are not only motivated, but scarcely aware of the indomitable figure who could win three majors in a season, no problem, who could take months of flex-time and return as though she hadn't missed a day.

Now? Serena Williams can no longer do tennis as a part-time gig. That was laid bare today. Under kiln-like conditions, she fell meekly -- as in 6-2, 6-3 meekly -- to No. 56-ranked Ekaterina Makarova, the lowest-ranked woman remaining in the round of 16 and a player inferior to Serena to an order of magnitude.

Let's dispense with the credit now. Makarova played crafty left-handed tennis. She transitioned gracefully from offense to defense and back again. Unlike so many similarly-situated opponents, when the match tightened, she didn't.

"I think she played really well," Serena said after the match. "She went for broke on a lot of her shots."

But mostly, she won by allowing Serena to self-destruct. She watched as miscast shots sailed beyond the court's parameters -- if not into Kia placards yards back of the court. She stood idly as serve after serve crashed into the net. The grim math: 37 unforced errors in 17 games, as well as seven double-faults. Not even Serena Williams wins playing like that.

"I made 37 errors," she added. "That kind of tells the story of the match."

Fighters lose a bout and may not compete again for months. The Baltimore Ravens and San Francisco 49ers will have a brutally long offseason to marinate in defeat; and almost eight months before they'll play another game. One of the virtues of the tennis caravan: there's always next week.

Except with Serena, there isn't. Her schedule, sparse in the best of times, has been pared to the four majors and the Olympics. Her chance for redemption won't come until late spring.

We will see if today's dismal result sharpens her resolve, whether it motivates her to make one last, earnest push toward the Evert-Graf-Navratilova corridor. Or whether this defeat further complicates what is already a complex relationship with the sport of tennis. This we know: she can't get away with doing this halfway anymore.